#include <3ds.h>
#include <citro3d.h>
#include <string.h>

#include "vshader_shbin.h"

#define CLEAR_COLOR 0x68B0D8FF

#define DISPLAY_TRANSFER_FLAGS                                                                                                      \
    (GX_TRANSFER_FLIP_VERT(0) | GX_TRANSFER_OUT_TILED(0) | GX_TRANSFER_RAW_COPY(0) | GX_TRANSFER_IN_FORMAT(GX_TRANSFER_FMT_RGBA8) | \
     GX_TRANSFER_OUT_FORMAT(GX_TRANSFER_FMT_RGB8) | GX_TRANSFER_SCALING(GX_TRANSFER_SCALE_NO))

static DVLB_s* vshader_dvlb;
static shaderProgram_s program;
static int uLoc_projection;
static C3D_Mtx projection;

static void sceneInit(void) {
    // Load the vertex shader, create a shader program and bind it
    vshader_dvlb = DVLB_ParseFile((u32*)vshader_shbin, vshader_shbin_size);
    shaderProgramInit(&program);
    shaderProgramSetVsh(&program, &vshader_dvlb->DVLE[0]);
    C3D_BindProgram(&program);

    // Get the location of the uniforms
    uLoc_projection = shaderInstanceGetUniformLocation(program.vertexShader, "projection");

    // Configure attributes for use with the vertex shader
    // Attribute format and element count are ignored in immediate mode
    C3D_AttrInfo* attrInfo = C3D_GetAttrInfo();
    AttrInfo_Init(attrInfo);
    AttrInfo_AddLoader(attrInfo, 0, GPU_FLOAT, 3);  // v0=position
    AttrInfo_AddLoader(attrInfo, 1, GPU_FLOAT, 3);  // v1=color

    // Compute the projection matrix
    Mtx_OrthoTilt(&projection, 0.0, 400.0, 0.0, 240.0, 0.0, 1.0, true);

    // Configure the first fragment shading substage to just pass through the vertex color
    // See https://www.opengl.org/sdk/docs/man2/xhtml/glTexEnv.xml for more insight
    C3D_TexEnv* env = C3D_GetTexEnv(0);
    C3D_TexEnvInit(env);
    C3D_TexEnvSrc(env, C3D_Both, GPU_PRIMARY_COLOR, 0, 0);
    C3D_TexEnvFunc(env, C3D_Both, GPU_REPLACE);
}

static void sceneRender(void) {
    // Update the uniforms
    C3D_FVUnifMtx4x4(GPU_VERTEX_SHADER, uLoc_projection, &projection);

    // Draw the triangle directly
    C3D_ImmDrawBegin(GPU_TRIANGLES);
    // Triangle 1
    // This vertex has r >= 0 and a >= 0 so the shader should output magenta (cmp.x = cmp.y = 1)
    C3D_ImmSendAttrib(200.0f, 200.0f, 0.5f, 0.0f);  // v0=position
    C3D_ImmSendAttrib(1.0f, 0.0f, 0.0f, 1.0f);      // v1=color

    // This vertex only has a >= 0, so the shader should output lime (cmp.x = 0, cmp.y = 1)
    C3D_ImmSendAttrib(100.0f, 40.0f, 0.5f, 0.0f);
    C3D_ImmSendAttrib(-0.5f, 1.0f, 0.0f, 1.0f);

    // This vertex only has r >= 0, so the shader should output cyan (cmp.x = 1, cmp.y = 0)
    C3D_ImmSendAttrib(300.0f, 40.0f, 0.5f, 0.0f);
    C3D_ImmSendAttrib(0.5f, 0.0f, 1.0f, -1.0f);

    // Triangle 2
    // The next 3 vertices have r < 0, a < 0, so the output of the shader should be the output of litp  with alpha set to 1 (cmp.x = cmp.y = 0)
    C3D_ImmSendAttrib(10.0f, 20.0f, 0.5f, 0.0f);
    // Output g component should be 64 / 128  = 0.5
    C3D_ImmSendAttrib(-1.0f, 64.0f, 0.0f, -1.0f);

    C3D_ImmSendAttrib(90.0f, 20.0f, 0.5f, 0.0f);
    // Output g component should be 128 / 128 = 1.0
    C3D_ImmSendAttrib(-1.0f, 256.0f, 1.0f, -1.0f);

    C3D_ImmSendAttrib(40.0f, 40.0f, 0.5f, 0.0f);
    // Output g component should be 0 / 128 = 0
    C3D_ImmSendAttrib(-1.0f, 0.0f, 0.5f, -1.0f);
    C3D_ImmDrawEnd();
}

static void sceneExit(void) {
    // Free the shader program
    shaderProgramFree(&program);
    DVLB_Free(vshader_dvlb);
}

int main() {
    // Initialize graphics
    gfxInitDefault();
    C3D_Init(C3D_DEFAULT_CMDBUF_SIZE);

    // Initialize the render target
    C3D_RenderTarget* target = C3D_RenderTargetCreate(240, 400, GPU_RB_RGBA8, GPU_RB_DEPTH24_STENCIL8);
    C3D_RenderTargetSetOutput(target, GFX_TOP, GFX_LEFT, DISPLAY_TRANSFER_FLAGS);

    // Initialize the scene
    sceneInit();

    // Main loop
    while (aptMainLoop()) {
        hidScanInput();

        // Respond to user input
        u32 kDown = hidKeysDown();
        if (kDown & KEY_START) break;  // break in order to return to hbmenu

        // Render the scene
        C3D_FrameBegin(C3D_FRAME_SYNCDRAW);
        C3D_RenderTargetClear(target, C3D_CLEAR_ALL, CLEAR_COLOR, 0);
        C3D_FrameDrawOn(target);
        sceneRender();
        C3D_FrameEnd(0);
    }

    // Deinitialize the scene
    sceneExit();

    // Deinitialize graphics
    C3D_Fini();
    gfxExit();
    return 0;
}